Device for feeding plastic rubber or synthetic rubber mixtures to processing machines

ABSTRACT

In combination with a processing machine, an apparatus in which a strip of natural or synthetic rubber material is fed at intervals into the charging funnel of the processing machine in conformity with the state of filling of the charging funnel, and in which between said feeding intervals a section of the strip of rubber material adjacent said charging funnel is cut off.

United States Patent Baumgarten 1 Jan. 23, 1973 [54] DEVICE FOR FEEDINGPLASTIC [56] References Cited RUBBER OR SYNTHETIC RUBBER UNITED STATESPATENTS MIXTURES TO PROCESSING MACHINES 3,036,335 5/1962 Heston et al...18 12 $11 UX 1751 Wmried Bil-Imam, 3011 P 3'523333 35133.llili'iifiifi: IIIIIIIIIIIIIIIIIIIIIi siTQ Germany 3,110,420 l1/l963Brewer ..1s/12 s11 11); 73 Assignee: c fi f Gummi werke Akfielb3,354,50l 5/1967 Bachman et al. ..l8/2 HA gesellschaft, Hannover,Germany Primary Examiner-H. A. Kilby, Jr. [22] Filed? 1970Attorney-Walter Becker [21] A l.N0.: 96 086 pp 1571 ABSTRACT [30]Foreign Appncation Priority Data In comhinatien with a processingmachine, an apparatus m wh1ch a strip of natural or synthetic rubberGermany 19 all material is fed at intervals into the charging funnel ofthe processing machine in conformity with the state of [52] US. Cl...'...425/142, 83/61,425/376 filling of the charging funnel, and inwhich between [51] hit. CIA. ..B78b 17/00 i feeding intervals a sectionof the Strip f rubber [58] Flew of Search 1 8/2 2 12 4 Si materialadjacent said charging funnel is cut off. 83/61; 425/142, 376

3 Claims, 2 Drawing Figures DEVICE FOE FEEDING PLASTIC RUBBER ORSYNTHETIC RUBBER MIXTURES TO PROCESSING MACHINES The present inventionrelates to an apparatus for feeding raw plastic natural and syntheticrubber mixtures in the form of a coherent strip into the charging funnelof extrusion presses or other processing machines. A frequently employedand highly satisfactory method of feeding such mixtures is based on theemployment of granulates or pellets inasmuch as in this way whenemploying weighing or dosing devices, it is possible to adapt theoperation to the varying discharge of the respective pertainingprocessing machine. Due to the required special granulating and pelletpreparing devices, methods employing granulates and pellets thereforenecessitate higher investment and operating costs.

According to another heretofore known method, the oncoming strips ofrubber material are formed into small zig-zag-shaped bands by .cuttingthe strips alternately from both sides, and these zig-zag-shaped bandswill, in view of their increased expandability in their longitudinaldirection during a continuous feeding to the processing machine, permitthe adaptation of the feeding operation within certain limits to thevarying discharge or extrusion output. Aside from the relatively highprice of the required zig-zag cutting device, the possibility ofemployment of this known method is limited to special instances withfixed condition of operation. A further drawback of the last mentionedmethod consists in that only strips of raw rubber mixtures with smoothlycut lateral edges are suitable.

It is, therefore, an object of the present invention to provide afeeding or charging system for feeding raw plastic natural and syntheticrubber mixtures into processing machines, which is applicablepractically for any universal feeding width without any limitingconditions and which will neither require any major structure whichmight affect the economy of the process nor any major investment costs.

This object and other objects and advantages of the invention willappear more clearly from the following specification in connection withthe accompanying drawings, in which:

FIG. 1 illustrates a side view of an apparatus according to the presentinvention with an extrusion press.

FIG. 2 is a front view of the apparatus according to FIG. 1.

The apparatus according to the present invention is characterizedprimarily by conveying means adapted to be driven in conformity with thefilling condition of the processing machine and receiving the strip ofraw rubber mixture,and is furthermore characterized by a cutting knifefor cutting the strip of raw rubber mixture, said knife being movablebetween the conveying means and the charging funnel.

According to a preferred embodiment of the invention, the conveyingmeans comprises a transport roller over a portion of which the strip ofthe raw rubber mixture is looped. The transport roller is adapted to bedriven intermittently and has associated therewith a pressure roller forpressing the strip against the circumference of the transport roller.The pressure roller is displaceable, for instance, by the thrust of aspring, by gravity or by a fluid pressure cylinder piston system.

Referring now to the drawings in detail, the apparatus shown thereinserves in the illustrated arrangement for feeding end portions of strip4 of a raw rubber mixture into an extrusion press 3. These strips 4 forma continuous coherent fleece which is alternately back and forth foldedcondition is in the form of a pile kept in readiness on a support 6adjacent the extrusion press. The extrusion press 3 may be of anystandard type with a motor transmission block 7 and a rotatable worm 9which plasticizes the charged raw mixture within a housing 8 providedwith a heating or cooling jacket. The worm 9 advances the charged rawmixture in the direction toward the non-illustrated mouthpiece of theextrusion press. The raw mixture is conveyed to the worm through acharging funnel 10 which is located at the rear end of the housing 8which faces away from the mouthpiece. During the rotation of the worm 9,the raw mixture is drawn inwardly and is intermixed with the content ofthe press while being subjected to increasing heating. For purposes ofsupporting and aiding this drawing-in effect of the worm 9, a feedingroller 11 may be provided which is driven in a direction opposite to thedriving direction of the worm 9 and is located within the region ofoperation of the worm 9. Roller 11 forms together with the worm 9 aroller gap or bite similar to the bite between the rollers of a mixingroller set. The charging funnel 10 may be charged directly or throughthe intervention of an additional conveying device, for instance, aroller conveyor or, in conformity with the illustrated embodiment,through the intervention of an endless conveyor belt 13 passed overreversing rollers 12. The direct charging of the relatively narrowcharging funnel is suitable for the processing of wide mixture fleecesand in general for the feeding of raw mixture strips having greatlyvarying widths.

The illustrated charging device comprises as primary components atransport roller 14 and a cutting knife 15 following the latter. Theroller 14 is in stationary bearings so journalled in the intake range ofthe charging funnel '10 that it will grasp the raw mixture strip passingover a guiding roller 16 on the upper rollercircumferential section andfeed the strip over and past the upper edge of the funnel into the same.The frictional engagement of the strip with the transport roller 14 isassured by a spring-loaded pressing roller 17 which is freely rotatablyjournalled and is radially displaceable toward the transport roller 14.The cutting knife 15 is designed as rigid impact knife having a lengthwhich corresponds approximately to the width of the rollers 14, 17. Theknife 15 is suspended in the manner of a pendulum on lever-shaped links19 and can be so tilted by a double-acting pressure fluid operablecylinder piston system 20 that it will simultaneously with the downwardmovement indicated in FIG. 1 by an arrow carry out a transverse movementparallel to the axial direction of the transport roller 14.Consequently, strip 4 is cut by means of pulling cuts which result in asaving of power and in smooth cutting surfaces. The alternate supply ofpressure fluid to both chambers of the cylinder piston system 20 iscontrolled by a non-illustrated electromagnetic valve the exciting coilof which is so interposed in the circuit of the driving motor for thetransport roller 14 that only an alternating actuation of the transportroller on one hand and of the cutting knife on the other hand will bepossible.

For the initiating pulse of the driving mechanism, the charging funnelof the extrusion press 3 is according to the illustrated embodimentprovided with photoelectrically scanned optically transparentperforations. At an adjustable height and in the region of the normalfilling level at both sides of the perforations there is provided aphotoelectric cell 21 with a pertaining light source 22 which blocks thepassage of the current as long as raw mixture is located within theoptically checked zone, and only when the light can pass through freely,closes the driving circuit. In a similar manner it would be possibleinstead to employ a mechanical feeler mechanism adapted to actuateelectric contacts.

The operation is as follows. The raw mixture strip 4 which is stored onthe support 6 adjacent the extrusion press is in steps or section bysection pulled forward by the intermittently driven transport roller 14.After each completed working cycle, a section or end portion of thestrip the length of which may be varied will behind the followingcutting knife extend into the region of the charging funnel 10 or theassociated conveyor 12, 13. During this feeding of the material, thecutting knife occupies its illustrated rest position. As soon as thepreviously charged strip section or end portion has been completelypulled into the extrusion press 3 and accordingly light can pass throughthe control section or end portion of the charging funnel, thephotoelectric cell initiates the driving pulse for the actuatingcylinder piston system of the cutting knife 15 so that the latter movesdownwardly, cuts off the next following strip section and directlythereafter returns to its rest position. by means of a limit switch orother suitable control means, subsequently the drive motor for thetransport roller 14 is turned on and the strip 4 is advanced by afurther section below the cutting knife. The apparatus is thereforeready to follow up with a new supply of material while the previouslycharged strip section has not yet completely passed through the intakezone.

As will be evident from the above, the apparatus according to thepresent invention requires relatively low investment costs andfurthermore permits a completely automatic operation without acontinuous manual intervention. The operator therefore can devote hisattention simultaneously to a plurality of devices in operation. Bothfactors increase the economy of the apparatus far beyond that ofheretofore known systems. In addition thereto, the possibility ofapplication of the apparatus according to the present invention is notbound to a certain condition or property of the raw mixture strip to beprocessed. The lateral edges need not be cut smoothly, and also varyingwidths of the strip will not affect the working operation. The cuttingknife which advantageously is actuated alternately with the transportroller is provided for completely cutting through the strip andtherefore can be designed in a simple cost-saving manner.

While the apparatus according to the invention has been designedprimarily for use in connection with extrusion presses, it is by nomeans limited thereto but may also advantageously be employed inconnection with the charging of other rubber or synthetic materialprocessing machines. The furnished raw mixture strips may be withdrawnfrom rotatably supported cops or rollers or the like or may be withdrawnfrom iles contaming the strips in alternately folded layers. he controlpulses for turning on the drive motor of the transport roller may bederived from standard control devices which photoelectrically ormechanically or in any other suitable manner feel or scan the conditionof filling of the charging funnel. The advance or feeding of the cut-offstrip section within the intake range of the processing machine may beaided by feeding rollers and/or by fluid pressure operable tampingmembers.

With regard to FIG. 2, there may be added that this figure also shows aphotoelectrically controlled circuit according to which the pressurefluid cylinder piston system 20 for the cutting knife 15 is through theintervention of a magnetic valve 28 provided with air under pressure atP while the magnetic valve is electrically controlled by a relay 26.Relay 26 is adapted on one hand to establish the control circuit for themagnetic valve 28 and on the other hand is adapted to establish thecircuit for the working current 27 for the drive motor 25 of thetransport roller 14. The drive motor 25 in its turn is controlled by aphotoelectric cell 21, 22.

It is, of course, to be understood that the present invention is, by nomeans, limited to the particular showing in the drawings but alsocomprises any modifications within the scope of the appended claims.

What I claim is:

1. In combination with an extrusion press having a charge inlet, stripfeeding means for feeding a strip of a rubber material, cutting means tosever end portions of said strip successively after being fed by saidfeeding means, means to direct said end portions successively to saidcharge inlet, control means to operate and stop said feeding means andto operate said cutting means when said feeding means is stopped, and asensing device in said charge inlet to actuate said control means tostop said feeding device and operate said cutting means in the absenceof an end portion in said charge inlet, and to operate said feedingmeans when an end portion is passing through said charge inlet.

2. In the combination claimed in claim 1, said extrusion press havingmeans for heating the material in the press.

3. In the combination claimed in claim 1, in which said cutting meanscomprises a knife movable transversely across the width of said strip ofrubber material.

t t t t

1. In combination with an extrusion press having a charge inlet, stripfeeding means for feeding a strip of a rubber material, cutting means tosever end portions of said strip successively after being fed by saidfeeding means, means to direct said end portions successively to saidcharge inlet, control means to operate and stop said feeding means andto operate said cutting means when said feeding means is stopped, and asensing device in said charge inlet to actuate said control means tostop said feeding device and operate said cutting means in the absenceof an end portion in said charge inlet, and to operate said feedingmeans when an end portion is passing through said charge inlet.
 2. Inthe combination claimed in claim 1, said extrusion press having meansfor heating the material in the press.
 3. In the combination claimed inclaim 1, in which said cutting means comprises a knife movabletransversely across the width of said strip of rubber material.